Nucl ear Magnetic Resonance Spectroscopy . The Effect of Structure on Magnetic Nonequivalence Due to Molecular Asymmetry
نویسنده
چکیده
Thc cliffcrcncc in chcmical shift bet$'cen the methl,lenc protons of a nuntber of compounds related structurally to l-phen1.lcth1.l bcnzy,l ether has been rneasured. correlations bct\veen structural features of these compounds .'rcl t5c mag.ituclc of the magnetic nrncquivalencc inclucecl b1'the center of molecuiarasvlllmetrl'provide ru. lxrsis f'r cl.alitlrti'c iclentihcation of the most important factors contributing to the chemical-shift difference' .\lthough it is clear that no single factor completell' clctermincs tire rnagnitude of the meth-r''lene proton non-equivalcucc in thcse ethcrs, it is suggeste(l that tl'," pro*i,rrit-v of the as1'nrmetric center to the benz]'l group results in a prcfcrreci conformltion of thc phenl'l ring rvith rcspect to the methl'lene protons, and that the principal contribution to thc ,r,r,r"q,,itnlcnce origiriates iir tire magnctic anisotropy of tire phenl'l group'
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